Study On The Determination Of Organic Pesticides Residues In Plant-based Foods

In this paper, organic tin and organic nitrogen pesticides that in a representative were chosen, matrix materials for the detection of pesticides was the domestic production of large use, high cost of citrus fruits and oilseed crops, the appropriate organic solvents wsa selected, accelerated solvent extraction (ASE) and liquid-liquid extraction (LLC) were chosen as method of extractor.macromolecular was impurited by Solid phase extraction (SPE) and gel permeation chromatography (GPC) in the samples, using gas chromatography with flame photometric detector (FPD)and nitrogen and phosphorus detector (NPD) respectively were detected and successfully determined a variety of pesticide residues.A capillary gas chromatographic (GC) method was developed for the determination of Fenbutatin oxide(FBT), Azocylotin and Cyhexatin residues in orange products. The sample was extracted with acetone-acetic acid (99:1, V/V) and HBr under acid circumstances, then extracted by hexane, and the residue was dissolved in hexane. organic tin was ethylated with ethyl magnesium bromide, then cleaned up with a Silica column, determined by GC. The standard curve was linear in the investigated range of 0.2 mg/L-2.0 mg/L. The correlation coefficients were more than 0.9995, the recoveries were 79.6%-109.6% with the relatives standard deviations of 3.60%-9.04%. The detection limit of Fenbutatin oxide was 0.1 mg/kg, Azocylotin and Cyhexatin were 0.02 mg/kg, It can be satisfied maximum residue limit requirement at home and abroad.In the organic nitrogen pesticide residues in the oilseed crops was extracted by ASE using acetonitrile as extracting agent, Beause the oilseeds sample were always in high oil content, so It was needed degresing some oil in the step of extract before cleanup. In this experiment, three different dispersant agent were compared: Alumina-N,Diatomaceous earth and Florisil. The data shows:Alumina-N was the great choose with good degresing effect, and the other two were not so well as Alumina-N, so Alumina-N was the best choose as dispersant agent,Then cleanup step is of great importance, because oil residues maybe demage the chromatography system, and GPC was popular with it high efficiency and excellent in automatization, and by comparing of different effect on the two mobile phases ethyl acetate:hexane (50:50, V/V) and dichloromethane:cyclohexane (50:50, V/V) of the standard material and samples, on the basis of gas chromatographic recoveries, the final selection of ethyl acetate:cyclohexane (50:50, V/V) as eluting agent. studying the blank sample by the trends of flow in the GPC and standards for substances in the outflow of GPC rules, determined the cut points. Then determined by GC-NPD, The standard curve was linear in the investigated range of 0.02 mg/L-2.0 mg/L. The correlation coefficients were more than 0.9990, the recoveries were 66.4%-112.2% with the relatives standard deviations less than 10%. The detection limit of nine organic nitrogen pesticides were 0.005 mg/kg-0.01 mg/kg. the detection limit was completely meeting the analysis requirements.